print("实际换行: Hello\nWorld")  # 实际换行效果

# r: 不会转义
raw_str = r"原始字符串: \n\t不会转义"
print(raw_str)  # 原始字符串: \n\t不会转义


text = "Hello Python Programming"
print(text[::2]) # Hlo Pto rgamn

print(text.isdigit()) # False

d = '123'
print(d.isdigit()) # True